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Biomedical subjects

W Dong

Publications and source records attributed to W Dong.

At least 127 records · Page 7Linked to original sources
PubMed1994

Capsid assembly and involved function analysis of twelve core protein mutants of duck hepatitis B virus.

The roles of different regions of the duck hepatitis B virus (DHBV) core protein on viral capsid assembly and related functions were examined. Twelve deletion and insertion mutations which covered 80% of the DHBV C open reading frame were constructed and expressed in Escherichia coli. The N-terminal region (amino acids 3 to 66) of DHBV core protein was important for its tertiary structure and function in E. coli. The expressed core mutants without this region apparently inhibited E. coli growth. The results of transmission electron microscopy of E. coli thin sections, capsid agarose gel, and sucrose gradient sedimentation demonstrated that a few DHBV core mutants with insertion in the N terminus and deletion in the C terminus retained the ability to form core-like particles in E. coli. However, other mutations in most of N-terminal and central regions strongly inhibited the self-assembly ability of DHBV core protein in E. coli. In addition, the mutant with a C-terminal region deletion (amino acids 181 to 228) lost most of the nucleic acid-binding activity of the DHBV core protein.

Amino Acid Sequence↗
PubMed1994

Effects of inhibitor of endothelium-derived relaxing factor on hypoxic contraction of isolated pig coronary artery.

Exposure of isolated pig coronary artery with endothelium intact to hypoxia Krebs-Henseleit solution aerated with 95% N2 + 5% CO2 caused a transient contractile response, and the coronary artery without endothelium exhibited a gradual decrease in basal tension. The endothelium-dependent contractile response to hypoxia was almost completely blocked by nitro-L-arginine (0.2 mmol.L-1), and inhibited by methylthioninium chloride (10 mumol.L-1). The inhibitory effect of the NLA was partially reversed by L-arginine (2 mmol.L-1). Sodium nitroprusside (10 mumol.L-1) was also completely antagonized and nicorandil (0.3 mol.L-1) remarkably reduced the hypoxic contractile response. Tetraethylammonium (10 mmol.L-1) and glibenclamide (1 mumol.L-1) had little effect on hypoxia-induced vascular contraction, whereas cromakalim (1 mumol.L-1) produced obvious relaxing effect on hypoxic response. These results suggest that suppression of basally released nitric oxide (NO) is an important mechanism of coronary vasoconstriction induced by hypoxia.

Animals↗
PubMed1993

Transcriptional interactions of transforming growth-factor-beta with pro-inflammatory cytokines.

BACKGROUND: Inflammation and tissue injury are characterized by a massive infiltration of mononuclear cells. These pro-inflammatory cells, which are the precursors of an inflammatory response by the immune system, secrete a variety of cytokines and growth factors that alter the biosynthetic repertoire of the resident connective tissue cells. Specifically, expression of connective tissue matrix metalloproteinases, such as stromelysin and interstitial collagenase, is enhanced, together with the expression of chemoattractants for leukocytes, such as interleukin-8 (IL-8). These events lead to increased connective tissue degradation. We have examined the growth factor regulation of expression in cultured fibroblasts of the prototypic pro-inflammatory factors interstitial collagenase and IL-8. RESULTS: We demonstrate that transforming growth factor-beta (TGF-beta) does not interfere with cytokine-induced IL-8 gene expression, nor does it affect the activity of NF-kappaB-driven promoters. In contrast, TGF-beta down-regulates collagenase gene expression through the induction of the jun-B proto-oncogene. Jun-B is a negative regulator of c-jun, which mediates cytokine activation of collagenase gene expression through its action as a component of the AP-1 transcription factor. CONCLUSION: Our data suggest that TGF-beta may attenuate the deleterious events that occur in inflammation by preventing cytokine-induced extracellular matrix degradation, although it does not affect cytokine-induced recruitment of pro-inflammatory cells. Furthermore, our data suggest a potential therapeutic use for jun-B, which may be a candidate for gene therapy in disease states that are characterized by excessive connective tissue degradation.

Journal Article↗
PubMed1993

Identification of a leucine-to-proline mutation in the keratin 5 gene in a family with the generalized Köbner type of epidermolysis bullosa simplex.

We have previously reported linkage of a large Finnish family with the generalized (Köbner) type of epidermolysis bullosa simplex to chromosome 12q in the region containing the type II keratin gene cluster (Ryynänen et al., Am J Human Genet 49:978-984, 1991). In this study, we examined the possibility that keratin 5, the type II keratin expressed in the basal keratinocytes, harbors the mutation in this family. Nucleotide sequencing revealed a T-to-C transition within exon 7 of the keratin 5 gene in the affected individuals of the family, while the unaffected individuals showed no evidence of C. The presence of the T-to-C transition in the affected individuals was confirmed by restriction enzyme digestion analysis with NciI endonuclease, as well as with PCR amplification of specific alleles (PASA) analysis. The PASA analysis also indicated that the mutated allele was not found among the 100 alleles tested within the general Finnish population indicating that the mutated allele is not a common polymorphism. Furthermore, the mutated allele was not present in nine individuals representing three different EBS families of Finnish origin. The T-to-C transition at the nucleotide level resulted in substitution of a leucine by a proline at the amino acid level, and the substitution affected a leucine residue which was invariant among eight different human keratins in a highly conserved segment at the carboxy-terminal region of the keratin 5 polypeptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Persistent dysregulation of IgA production and IgA nephropathy in the B6C3F1 mouse following withdrawal of dietary vomitoxin (deoxynivalenol).

To assess whether vomitoxin-induced dysregulation of IgA production and IgA nephropathy are reversible, relevant immunologic parameters were compared among experimental groups of B6C3F1 mice that were fed: (1) 25 ppm vomitoxin in AIN-76A semipurified diet for 24 weeks (treatment group), (2) 25 ppm vomitoxin for 8 weeks and then control diet for 16 weeks (withdrawal group), and (3) control diet for 24 weeks (control group). Levels of serum IgA and microhematuria index in the treatment group were elevated after 4 to 8 weeks and continued to increase with further vomitoxin exposure. IgA immune complexes and mesangial IgA deposition, as quantitated by interactive laser cytometer image analysis, were also increased with toxin exposure at Weeks 8, 16, and 24, whereas IgM, IgG, and complement component C3 deposition were unaffected or depressed. Serum IgA, microhematuria index, and mesangial IgA deposition in withdrawal mice remained elevated over those of the controls at Weeks 16 and 24 but were less than those of the treatment group. Cell recovery from Peyer's patches (PP) as well as the percentages of IgA+ and CD4+ cells in PP and spleen at Weeks 16 and 24 were greater in treatment mice than in controls, but only the percentage of IgA+ cells in PP was elevated in the withdrawal mice at these the same time points. When IgA secretion by unstimulated and LPS-stimulated splenic lymphocytes was used as the measure of systemic production, it was elevated in both treatment and withdrawal mice at Weeks 16 and 24. The results indicated that experimental dysregulation of IgA production and IgA nephropathy persisted up to 4 months after a discrete period of dietary vomitoxin exposure, but that the severity of these effects did not increase in a progressive fashion.

Animals↗
PubMed1993

In vitro vomitoxin exposure alters IgA and IgM secretion by CH12LX B cells. Relationship to proliferation and macromolecular synthesis.

The CH12LX cell line was used as a clonal model to assess the direct effects of vomitoxin on IgM and IgA secretion in B cells. When vomitoxin was included in LPS-driven CH12LX B cell cultures, it had multiple effects on Ig secretion. Whereas vomitoxin doses of 115 and 120 ng/ml caused 50% inhibition (ID50) of IgA and IgM production, respectively, toxin concentrations in the 5 to 50 ng/ml range slightly stimulated IgA production. However, low vomitoxin doses did not induce switching of membrane IgM+ CH12LX B cells to membrane IgA+. Total cell number was unaffected at vomitoxin concentrations up to 100 ng/ml but dropped markedly at 200 ng/ml (ID50 = 170 ng/ml). Using the MTT reduction assay as another measure of viability and cell function, vomitoxin was also inhibitory (ID50 = 130 ng/ml). Both thymidine incorporation and leucine incorporation were also inhibited by the toxin with estimated ID50s being 120 and 110 ng/ml, respectively. The results indicate that although at high doses, vomitoxin inhibits proliferation, Ig secretion and DNA/protein synthesis in the clonal B cell model, the toxin marginally stimulated IgA secretion at lower doses.

Animals↗
PubMed1993

Detection of HCV infection by cPCR in patients with acute leukemia.

HCV RNA and anti-HCV were detected respectively by complemented DNA polymerases chain reaction (cPCR) and ELISA in the sera of 28 acute leukemia patients with repeated blood transfusion and changes in liver function. HCV RNA positive rate was 78.6%. Anti-HCV positive rate was 60.7%. 25 subjects showed positive results in HCV RNA or anti-HCV, or in both of them. By combined assessment, the HCV infection rate was 89.3%. Acute leukemia patients were the high risk group of HCV infection because of the lowered immune function and repeated blood transfusion. By cPCR, HCV RNA can be detected earlier and the sensitivity is higher than by anti-HCV. So cPCR is a sensitive and specific method for early diagnosis of HCV infection. The combination of HCV RNA and anti-HCV detection methods may improve the diagnostic rate of HCV infection.

Adolescent↗
PubMed1993

Study on cytomegaloviral infection in acute leukemia patients by polymerase chain reaction.

Polymerase chain reaction (PCR) and blot hybridization by probe labelled with digoxin were used to detect human cytomegalovirus (HCMV) DNA in 31 patients with acute leukemia and 20 controls. The positive rate detected by PCR in acute leukemia was 74.2% and 15.0% in the controls. The difference was statistically significant. The results suggest that acute leukemia patients are the high risk population with high infection rate of HCMV. The positive rate detected by digoxin method in acute leukemia was 58.1%. Six patients showed negative results by digoxin method, but positive by PCR. It was demonstrated that PCR was superior to digoxin method in sensitivity. Anti-HCMV IgM in serum of patients was detected at the same time, the positive rate was 16.1%. Only 6 of the 23 PCR positive patients showed positive anti-HCMV IgM. It suggests that the immune response is weak in acute leukemia patients and HCMV recently infected could not be excluded in the anti-HCMV IgM negative cases.

Adult↗
PubMed1993

[Alternative combination chemotherapy with mitomycin C, vincristine, methotrexate, 5-fluorouracil, cis-platinum and adriamycin for adenocarcinoma of the lung].

Efficacy of an alternative combination chemotherapy with MMC, VCR, MTX, 5-FU, CDDP and ADM for adenocarcinoma of the lung is reported. Forty-one advanced cases (stage III: 9; IV: 32) were chosen for the chemotherapy. Two combination chemotherapies MMC + VCR + MTX + 5-FU + CDDP: MVMFP; MMC + VCR + MTX + 5-FU + ADM: MVMFA were repeated alternatively for 8 consecutive weeks with 2 interposed rest weeks, and this regimen was completed in 34 cases. All 41 cases were evaluable. Three and 26 cases achieved complete and partial responses, respectively. The response rate was 70.7%, and the median survival time was 13 months. The adverse effects of the chemotherapy observed were tolerable: alopecia (63.4%), gastrointestinal symptoms (14.5%), bone marrow toxicity (12.2%) and liver dysfunction (4.8%). These results indicate that our MVMFP/MVMFA alternative chemotherapy is quite effective for adenocarcinoma of the lung, comparable or superior to conventional chemotherapies.

Adenocarcinoma↗
PubMed1992

Effects of various noise exposures on endocochlear potentials correlated with cochlear gross responses.

Changes in endocochlear potentials (EP), cochlear microphonics (CM), and compound action potentials (CAP) with noise exposure were investigated in guinea pigs. The animals were anesthetized and immobilized and exposed to white noise at intensities ranging from 105 to 125 dB. The negative EP (N-EP) was induced by anoxia and was investigated during and after noise exposure. It was found that the general EP (G-EP, the sum of both positive EP (P-EP) and N-EP) increased remarkably during exposure to 115 dB noise but decreased during exposure to 125 dB noise. A smaller absolute value of N-EP was encountered only during exposure to 125 dB noise. The results shed light on the relationship between EP and CM, CAP changes, and the potential mechanism of EP change and its significance in noise-induced hearing loss.

Acoustic Stimulation↗
PubMed1992

Baculovirus phosphoprotein pp31 is associated with virogenic stroma.

The PstI K fragment of Autographa californica nuclear polyhedrosis virus (AcMNPV) encodes a protein with a molecular weight of 31,000. To define the role of this protein (pp31) in virus infection further, it was overexpressed in bacteria and used to produce polyclonal antiserum. Radioimmunoprecipitation analysis indicated that pp31 was synthesized during both the early and late phases of virus infection, consistent with previous analyses indicating that the gene was regulated by tandem early and late promoters. Metabolic labeling of cells with carrier-free phosphate indicated that pp31 was phosphorylated. Biochemical fractionation experiments showed that pp31 was localized in the nucleus and that it was more stably associated with the nucleus at later times of infection. Immunoblot analysis of subnuclear fractions indicated that pp31 was associated predominantly with the chromatin and nuclear matrix fractions. Immunofluorescence experiments confirmed that the pp31 protein was localized in the nucleus. Nuclear staining was relatively uniform early but was more centrally nuclear later in infection. Immunoelectron microscopy indicated that the pp31 protein was a component of virogenic stroma. Southwestern (DNA-protein) blot analysis demonstrated that pp31 is a DNA-binding protein. These findings suggest a possible role for pp31 in the virus life cycle.

Animals↗
PubMed1992

[Protective action of phenytoin on cerebral ischemia in rats].

In order to study and modify the ischemic brain lesions, protecting the reversible damage of neurons, and limiting the ischemic damage both models of cerebral ischemia--focal cerebral ischemia induced by photochemically, and brain reperfusion after ligation of common carotid arteries bilateral in Wistar rats were used to investigate the protective effect of diphenylhydantoin (DPH) on cerebral ischemia. Two groups of rats received DPH 10 mg/kg and 30 mg/kg respectively were compared with those having received normal saline immediately after cerebral ischemia. The effects of DPH on the changes of EEG, biochemical marker and pathologic lesion in focal cerebral ischemia in rats were evaluated. The results showed that the degree of restoration of EEG in the group treated with DPH was better than in the group with normal saline, the content of water in ischemic cerebral tissue was decreased significantly (P < 0.05), the activity of Na-K-ATPase and antioxidant was increased significantly (P < 0.01, P < 0.05, respectively), and the percentage of necrotic neurons in periischemic area was decreased markedly (P < 0.001) in groups treated by DPH. The results suggest that there is a definite protective effect of DPH on cerebral ischemia.

Animals↗
PubMed1991

Quantitative assessment of mesangial immunoglobulin A (IgA) accumulation, elevated circulating IgA immune complexes, and hematuria during vomitoxin-induced IgA nephropathy.

Extended dietary exposure to the trichothecene vomitoxin (deoxynivalenol), a naturally occurring fungal contaminant of cereal grains, induces elevated serum IgA and mesangial IgA accumulation in a manner similar to the human glomerulonephritis, IgA nephropathy. A 12-week feeding study was conducted in the B6C3F1 mouse to evaluate the effects of exposure to 25 ppm dietary vomitoxin over time on formation of IgA immune complexes (IgA-IC), hematuria, and mesangial deposition of IgA, IgG, IgM, and complement component C3. Both serum IgA and IgA-IC were significantly elevated in vomitoxin-exposed treatment groups compared to controls at weeks 4, 8, and 12, whereas serum IgG was unaffected. The incidence of hematuria was also significant in vomitoxin-exposed mice at weeks 4, 8, and 12. Quantitative immunofluorescence intensity measurements using interactive laser cytometer image analysis revealed significantly greater mesangial IgA accumulation in vomitoxin-fed mice compared to controls at weeks 4, 8, and 12. Although glomerular IgG and IgM deposition was present in both controls and treated mice, it was significantly lower in treated mice as compared to controls at week 12. Mesangial C3 deposition was not induced by vomitoxin feeding. Elevated IgA-IC, hematuria, and IgA mesangial accumulation occurring during exposure to vomitoxin mimicked human IgA nephropathy, whereas the absence of mesangial C3 represented a major difference between this toxin-induced immune dysregulation and the human disease.

Animals↗
PubMed1991

Expression of an enhancer-binding protein in insect cells transfected with the Autographa californica nuclear polyhedrosis virus IE1 gene.

The baculovirus Autographa californica nuclear polyhedrosis virus contains an element known as homologous region 5 (hr5) which is an enhancer of delayed-early viral gene expression. To begin to identify proteins that interact with hr5, DNA-protein interactions were analyzed by using extracts from Spodoptera frugiperda cells and a fragment of DNA containing the left half of the hr5 enhancer. This 252-bp DNA fragment contains two copies of a 30-bp direct repeat (DR30) and two copies of a 24-bp imperfect palindrome contained within a 60-bp direct repeat (DR60). Extracts prepared from normal S. frugiperda cells and cells transfected with pUC8 lacked enhancer-binding proteins. However, when gel shift assays were performed with extracts from cells transfected with a plasmid containing the viral trans-activator IE1 gene, two DNA-protein complexes were formed. Both DNA-protein complexes were specifically inhibited by competition with a 60-bp oligonucleotide corresponding to DR60 but not by competition with a different oligonucleotide corresponding to DR30. Formation of the two complexes did not appear to involve cooperative interactions between binding proteins. When DR60 was used as a probe, a single complex was formed. To measure the enhancer activity of DR60, a reporter plasmid was constructed that contained DR60 cloned upstream of the reporter chloramphenicol acetyltransferase gene under the control of the delayed-early 39K promoter. Transient expression analysis indicated that the oligonucleotide increased expression of this gene 300-fold over the level obtained in the absence of any enhancer sequences.

Animals↗